Method of producing abrasive elements



July 15. 1924. 1,501,229

c. G. OLSON v METHOD OF PRODUCING ABRASIVE ELEMENTS v Fiied Oct. 12 1921 4 Sheets-Sheet 1 c. G. OLSON METHOD OF PRODUCING ABRASIVE ELEMENTS Juiy 15', 1924. 1,501,229-

' Filed Oct. 12 1921 4 Sheets-Sheet 2 ag/z 7/74 @WZW. 6?? G 02507? Jul 15, 1924. 1,501,229 c. G. OLSON v y METHOD OF PRODUCING ABRASIVE ELEMENTS Filed 05a. 12 1921 4 Sheets-Sheet a July 15 1924.

C. G. OLSON METHOD OF PRODUCING ABRASIVE ELEMENTS Filed Oct.- 12

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Patented July 15, 1924.

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CARL G. OLSON, OF CHICAGO, ILLINO'IS, ASSIGNOR TO ILLINOIS TOOL WORKS, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

METHOD OF PRODUCING ABRASIVE ELEMENTS.

Application filed October 12, 1921. Serial No. 507,219.

To all whom it may concern:

Be it known that I, CARI. G. OLsoN, a

citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented arertain new and useful Improvement in Methods of Producing Abrasive Elements, of which the following is a specification.

My invention resides in a process for dressing or truing ring-like and helicoidal tools especially those made of abrasive material. My process is particularly adapted for the production of abrasive hobs so called, which operate somewhat after the manner of an ordinary toothed hob for producing gears and the like, but have no teeth and instead of cutting the metal, dress or true the surface by grinding it. The object is to provide a process capable of producing such articles and accomplishing the work accurately, simply and etficiently.

I obtain my object in the manner illustrated in the accompanying drawings in which Figure 1 is an assembly view, viewed from the top showing my process as applied to a helicoid or threaded abrasive tool.

Figure 2 is a diagrammatic view illustrating the theory of the invention and the manner in which the orbit of a diamond point may conform in part to the surface of the helicoid to dress it.

Figure 3 is an end view looking toward the left of Figure 2.

Figure 4 is a diagrammatic v1ew 1llustrating the manner by which a plurality of cuts or scarfs may dress the entire surface.

Figure 5 is a side view of a ring type of tool where the sides of the ring are perpendicular to the axis.

Figure 6 is a diagrammatic view illustrating a practical method for adplstlng the diamond point or other scarifymg tool employed in connection with my present process.

Figure 7 is an edge view of an abrasive.

tool having a convex surface. This figure illustrates diagrammatically how such a surface can be produced by my process.

Figure 8 is a plan view of the parts shown in Figure 7.

Figure 9 is an edge view of an abrasive tool having a concave surface. Thls figure illustrates diagrammatically how such a surface can be produced by my process.

Figure 10 is a plan view of the parts shown in Figure 9.

Figure 11 is an assembly view illustrating a modification in the process, to produce special surfaces. In this case the diamond point has an axial movement in addition to its rotary movement.

Figure 12 is an assembly view showing my process applied to a threaded tool or abrasivehob which is of a conical or taper form.

F igure 13 is an end View of some of the parts shown in Figure 12.

Like numerals denote like parts throughout the several views.

As my process is of special utility in connection with the production of ring like and helicoidal abrasive tools I shall describe it primarily in that connection. I propose to preform the work to approximately the configuration desired, the preforining being accomplished by moulding or othersuitable method. My present process is intended simply to finish the work and bring it accurately to form. H

To impart a preliminary idea of the principle involved, it may be stated that in carrying out my process, I first determine the location of a circle having an are which will lie in'the desired surface, the axis of such circle to lie outside of the body of the work. I then mount a diamond point or other scarifying tool in such manner that it will revolve in an orbit which will include said are. I then cause said tool to re volve at high speed and at the same time cause the work to rotate slowly about its own axis. The work and scarifying tool are caused to rotate at such relative speeds that the small grooves or scarfs produced by the tool, will, in the aggregate, cover the entire surface to be finished and leave it in the exact form desired.

The drawings are more or less diagrammatic and are intended to merely illustrate the principleof the invention.

Referring first to Figure 1, the work 1 is shown in the form of a helicoid mounted upon a work arbor 2. Said arbor is supported at one end by a center 4 located at the head of a lathe or similar machine tool. Said center rotates in unison with the drive shaft 5 journaled in the head stock 6. The opposite end of the arbor is supported upon a center 8 mounted in the tail stock 10. In

practice the head stock. shaft 5 rotates 4 I a bracket 25 mounted upon a shank 26 seslowly and the rotary motion is imparted to the work arbor bya dog 12 in the usual cured to a tool post 28 in any suitable manner. Said tool post is mounted upon a carriage 30 adapted to slide on ways 31which arearranged in the present case parallel to the axis of the work, The travel of the car- 'riage iseffected by a lead screw 32 which in "practice is caused to rotate at a predetera. nnined speed ratio with the speed of the work 2o arbor. The tool carriage and its appurtenances may be greatly varied 1n design, the

point being that means are provided for causing the arm 15 to. revolve athlgh speed and to simultaneously travel in harmony with the lead of the helix of the work.

- A practical'method for adjusting thescarifyingtool and its support is illustrated in Figure 5. Let 40 represent the side of f I one'of the threads of-thehelicoid to be produced. Against this surface the operator j lays the knife-edge 41 of a ring 42. This ringmay be termed the test ring. The 1 diameter. of its knife edge is equal to the diameter of the orbit ofthe diamond point 16. (In other words, saidknife edge is of a diameter" equal to twice the distance of the v diamond point from its axis of revolution.

When the ring'thusxcomesto rest against the side of the helicoid it will contact the same thruout an are 46,: 4:7, 48, illustrated I in dotted lines, Figures 2 and 3. The direc tion which the axis of the test ring now [assumes will be the proper position for the tool is cause axis of the tool spindle 18. If now, the tool spindle is adjusted to this position, and the and the tool carriage is moved along by the lead screw 32 at the proper ratedetermined by the lead or pitch of the helicoid, said tool will produce a series of arcuate scarifications indicated at A, Figure 4. In the drawing cutting these small cuts, scarfs-or grooves are shown a .far enough apart to be readily distinguishiable, the purpose being to illustrate the priniPI; but in practice they are so close toigether asto be contiguous, and in the aggregate'cover the entire surface, thus dressing I 1t, or bringing it to true form.

.In'the form of work shown in Fi rel t [flier the: manner of an. ordinary gearhob; In "such'case'the axis of the scarifyingtoolwill lie obliquel'yto the axis of-the'jwork. In the case of rings or collars,

to revolveat high speed and, the work is caused to rotate at slow speede thre'adsare helicoidal and their si es are where the sides lie in plane perpendicular to the axis of rotation, the axis of the scarifying tool will lie parallel to the axis of rotation to the work, see Figure 6. The process is applicable, however, to other variations in the configuration of the work. In Figures 7 and 8 the work is in the form of a disc 52 having convex sides. In such case the tool spindle will lie obliquely, the orbit of the scarifying tool being represented by the dotted line 54.. In the Figures 9 and 10 the work is in the form of a disc 56 having a concave side. In such case the tool spindle will lie obliquely, the orbit of the scarifying tool being represented by the dotted line 58. It will be understood that by causing the scarifying tool to travel parallel to the axis of the work, helicoidal surfaces similar in profile to those shown in Figures 6 to 10 may be produced.

In some cases it may be desirable to produce helicoids, the threads whereof have profiles showing compound curves, as for example in Figure 11. Here the line from the point to the point 71, is of sueh configuration that it can be produced by a scarifying tool whose orbit lies in a plane as before, the remaining portions of the curve, as at 74'and 75, being sharper. To produce these special curvatures it is necessary to warp the orbit. accomplished by mechanism illustrated in Figure 11, the scarifying tool 15 being mounted on a tool spindle 80 which is slideable as well as rotatable in a casing 82.

At the rear end the casing has a cam 85 adapted to be engaged by the nose 86 formed on a collar 88 rigidly secured to spindle 80.

This may be A compression spring 90 constantly urges I the spindle in a direction to keep the collar 88 in close contact with. cam 85. This spindle is driven by 'a sheave 22 as before. It will be evident that by properly designing the cam, the diamond point will have a compound movement which will produce the profile desired. In order to permit the scarifying tool to completely finish the root of the curve it is desirable to form a channel 92 in the body of the work at the root of the threads. I

"The first type of abrasive hob shown in Figure 1 and elsewhere must be fed thru the work parallel to the axis thereof, after the manner of an ordinary hob so that as the grinding progresses it will produce straight and parallel gear teeth. Differently stated, as the lineal elements .of the teeth of ordinary involute gears are straight-lines, the grinding hob, as the work progresses, must be fed in a direction parallelto the axis of the gear wheel. I, have conceiveda second type of grinding hob, however, the

same being illustrated in Figures 12 and 13. This second type has a conical body 60, and the helicoidal thread is formed upon the surface of the cone in such, manner that one side 62 of the thread is nearly at right angles to the hob axis and therefore presents practically a fiat surface to the teeth of the 7 does the grinding is ideal for all practical purposes. The flat sides of the thread become analogous to the sides of a rack, the pitch line whereof is represented by the dotted line 66-66, Figure 12. In such case, it will be evident that the curvature of the periphery of the grinding hob .will cut slightly deeper in the middle of the bottom of the spaces between the teeth to be dressed,

but this can do no practical harm, as the diameter of the grinding hob is comparatively great in proportion to the width of the face of the gear to be ground.

In using the conical type of abrasive hob shown in Figures 12 and 13 ordinarily the gear to be dressed will be rotated in harmony with the lead of the helix by means of an interconnecting gear train in a manner analogous to the hobbing of spur gears. However, the gear to be dressed maybe rotated simply by the action of the hob itself. In this event a friction device will be desirable so that the surface to be ground engage the arbor'64 on which the gear is fastened. The amount of friction may be regulated by a stud 100 having a head 101 and engaging one of the brake arms and a nut 102 engaging the other.

The mountin of the scarifying tool will be similar to t e one previously described except that the lead screw 110 will be arranged at an oblique angle with the work arbor 112. The Ways 113 on which the carriage 114 slides will, of course, be parallel to said lead screw. The work arbor and the shaft 116 by=which the lead screw is driven will be geared together by bevel gears 118, 119.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is 1. The process of dressing preformed helicoidal and annular surfaces formed on bodies which are rotatable about on axis, said process consisting in causing the point of a pointed scarifying tool to rotate at high speed in an orbit an arc of which lies in the surface to be dressed, and simultaneously causing the work to rotate about its own axis, the tool thereby producing a series of scarfs which, in the aggregate, envelop the surface to be produced.

.2. The process of dressing helicoidal and annular surfaces formed on bodiesof abrasive material which are rotatable about an axis, and substantially symmetrical with respect to that axis, said process consisting in causing a scarifying tool to rotate at high speed in an orbit an arc of which lies in the surface to be dressed and simultaneously causing the work to rotate slowly about its own axis.

3. The process of dressing abrasive heli- 'coids consisting in causing a scarifying tool to travel in an orbit a segment of which lies in the helicoidal surface, simultaneously causing the rotation of the helicoid about its axis, and simultaneously causing relative travel, bodily, between the grinding point and the helicoid in a direction parallel to the pitch line of the helicoid.

4- The process of dressing abrasive helicoids consisting in causing a scarifying tool to travel in an orbit a segment of which lies in the helicoidal surface, simultaneously causing the rotation of the helicoid about its axis, and simultaneously causing relative travel, bodily, between the grinding point and the helicoid in a direction parallel to the axis of th helicoid.

5. The process of dressing abrasive helicoids consisting in causing a scarifying tool to revolve about an axis in contact with the helicoidal surface of the work, simultaneously shifting the tool in an axial direction, simultaneously causing the work to revolve, and simultaneously causing relative travel, bodily, between the tool and the work in a direction parallel to the pitch line of the helicoid and at a rate in harmony with the lead of the helicoid.

6. The process of dressing abrasive helicoids formed on cylindrical bodies, said process consisting in determining the osition of a circle an arc of which will he in the helicoidal surface approximately from crown to root, causing a scarifying tool to travel in said circle, rotating the work, and causing bodily travel of the tool and work in a direction parallel to the axis of the work in harmony with the pitch or leadof the helicoid.

In witness whereof, I have hereunto subscribed my name. 

